Metal foil catalyst for the control of emissions from diesel engines

ABSTRACT

A diesel engine emissions catalyst which may be used to fill a niche between standard oxidation catalyst and diesel particulate filters for control of diesel particulate matter. The catalyst includes a structure (substrate) comprising one or more coated, corrugated micro-expanded metal foil layers. The coated surface may be a high surface area, stabilized, and promoted washcoat layer. The corrugated pattern may include a herringbone-style pattern that, when in use, is oriented in a longitudinal direction of the diesel engine exhaust flow. The micro-expanded metal foil provides small openings or eyes that, as the exhaust flow passes through the catalyst (transverse to the eye opening), particulates in the flow impinge on the surface and becomes trapped in the eyes. The catalyst may be used to treat a locomotive engine exhaust stream and may be used with a selective catalyst reduction system.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.17/052,735 filed Nov. 3, 2020, which is the United States National Phaseof PCT Application No. PCT/US2019/013433 filed 14 Jan. 2019, whichclaims priority to U.S. Provisional Patent Application No. 62/667,026filed 4 May 2018, each of which is incorporated herein by reference.

BACKGROUND

This disclosure is in the field of catalysts and, more particularly,catalysts intended to treat emissions from diesel engines such as, butnot limited to, diesel engines used in non-road applications.

Emission standards for non-road diesel engine emissions have beenincreasingly tightened through the years. Examples of this are EPA Tier4 emission standards. In some applications, nitrogen oxide (“NOx”)emissions cannot be greater than 5 ppm to 10 ppm and may require 99%reduction efficiency. Diesel emissions contain diesel particulate matter(“DPM”) comprised of about 80% unburned diesel fuel, referred to as thesoluble oil fraction, and elemental carbon particles. To date, DPMcontrol has primarily focused on engineering improvements to theengines. However, the cost and availability of the improvements has notmet industry needs, leading to other solutions like exhaustafter-treatment. Exhaust after-treatment solutions include oxidationcatalysts and diesel particulate filters or wire meshes. Oxidationcatalysts, which may employ either ceramic or metal foil basedsubstrates various cell densities and geometrical shapes, typicallyachieve a 20% to 40% conversion of DPM and can have a short operationallife. Diesel particulate filters achieve higher conversion, about a 95%conversion or more. However, the filters induce a higher backpressure onthe engine, thus robbing horsepower. The filters also require in-situregeneration and may require frequent cleaning to remove non-combustibleparticulate debris. Additionally, the oxidation catalysts and filtersmay not provide a suitable solution for many types of diesel engineapplications and their associated emission requirements.

SUMMARY

A diesel engine emissions catalyst of this disclosure may be used tofill a niche between standard oxidation catalyst and diesel particulatefilters for the control of diesel particulate matter (“DPM”). Inembodiments, the catalyst, which may be referred to as a dieseloxidation trap catalyst (“DOTC”), includes a structure (substrate)comprising one or more coated, corrugated micro-expanded metal foillayers and a frame housing or encapsulating the substrate. The coatedsurface may be a high surface area, stabilized, and promoted washcoatlayer. The corrugated pattern may include a herringbone-style patternthat, when in use, is oriented in a longitudinal direction of the dieselengine exhaust flow. The micro-expanded metal foil provides smallopenings or eyes that, as the exhaust flow passes through the catalyst(transverse to the eye opening), DPM in the flow impinges on the surfaceand becomes trapped in the eyes. In some embodiments, the catalyst maybe used to treat a locomotive engine exhaust stream. In otherembodiments, the catalyst may be used to treat a marine diesel engineexhaust or other heavy duty, non-road diesel engine exhaust stream. Thecatalyst may be used in connection with a selective catalyst reduction(“SCR”) system that mixes exhaust with ammonia. Embodiments of a methodfor reducing diesel particulate emissions may include passing or flowinga diesel engine exhaust gas flow through a diesel engine emissionscatalyst of this disclosure. Removal efficiencies may be in a range of55% to 85%, there being subranges within this broader range.

An engine emissions catalyst of this disclosure may comprise a substrateincluding one or more coated, corrugated, micro-expanded metal foillayers, each of said layers containing a plurality of eyes containingopenings in a range of about 0.002 in to about 0.08 in (0.058 mm to2.032 mm); a coating of each said layer including a washcoat layer and aprecious, the washcoat layer being in a range of 80.5 g/l to 102.5 g/l,including a metal oxide, and having a porous surface area in a range of100 m²/g to 250 m²/g (488,246 ft²/lb to 1,220,616 ft²/lb) of the metaloxide, the precious metal being in a range of about 2 g/ft³ to about 40g/ft³ (0.071 g/l to 1.41 g/l); flow channels per unit area of a face ofthe substrate being in a range of about 100 cells/in² (15 cells/cm²) toabout 400 cells/in² (62 cells/cm²); and a frame housing the substrate.The washcoat layer may include at least one rare each oxide, a promoter,or both the rare earth oxide and the promoter.

A metal of the metal foil layers may include chromium and aluminum. Themetal foil layer may be a heat treated metal foil layer. The metal foillayer may be an acid etched or a thermally treated metal foil layer. Theprecious metal may be platinum. The metal oxide may include aluminumoxide. The coating may include a rare earth oxide or a promoter or both.Each metal foil layer may include a corrugated pattern configured fororientation in a longitudinal direction of a diesel engine exhaust flow.The corrugated pattern may be a herringbone pattern.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a photograph showing a top plan view of an embodiment of amicro-expanded metal foil layer of a diesel emissions catalyst of thisdisclosure after passing through a corrugation process. The darker bandsare shadows caused by a herringbone-type pattern of the corrugatedmicro-expanded metal foil shading the light.

FIG. 2 is a top plan schematic view of a layer of an embodiment of amicro-expanded metal foil of this disclosure prior to corrugation toemboss a herringbone-style pattern on the foil.

FIG. 3 is a side elevation schematic view of the micro-expanded foil ofFIG. 2 after corrugation.

FIG. 4 is a side elevation schematic view of a layered stack of themicro-expanded foil of FIG. 2 . In embodiments, the each layer may be incontact with adjacent layers.

FIG. 5 is an electron microscopic image of an embodiment of a coated,corrugated micro-expanded foil of this disclosure.

FIG. 6 is an electron microscopic image of an embodiment of thisdisclosure showing captured diesel particulate matter on the surface andin the “eyes” of the catalyst.

FIG. 7 is a schematic of an embodiment of a selective catalyticreduction (“SCR”) system in which the diesel emissions catalyst of thisdisclosure may be used.

FIG. 8 is a photograph of a top plan view of an embodiment of themicro-expanded metal foil.

FIG. 9 is a photograph of a top plan view of a layered stack of thecoated, corrugated micro-expanded foil,

FIG. 10 is a graph showing removal efficiency results in a 3000-hourexperimental field test of a catalyst of this disclosure, with Case 1being typical for locomotive moving a train over a distance and Case 2being typical for a locomotive moving cars around a train yard in theact of assembling a train for eventual distance travel.

ELEMENTS AND NUMBERING USED IN THE DRAWINGS AND DETAILED DESCRIPTION

-   10 Diesel engine emissions catalyst (diesel oxidation trap catalyst    or “DOTC”-   11 Structure or substrate-   13 Micro-expanded metal foil layer-   15 Frame-   17 Micro-expanded metal foil-   19 Openings or eyes of 17-   21 Coated surface-   23 Washcoat layer-   25 Corrugated pattern-   27 Flow channels-   29 Catalyst face-   30 Selective catalyst reduction (“SCR”) system-   31 Injector-   33 Mixing process-   35 SCR reactor-   37 DOTC reactor-   L Longitudinal direction relative to exhaust flow-   T Transverse direction relative to exhaust flow

Definitions

For the purpose of this disclosure, the following definitions apply.

A layer is a single sheet, quantity, or thickness of a material (e.g.one sheet of metal foil or one washcoat thickness) as opposed tomultiple sheets, quantities, or thicknesses of materials.

A micro-expanded metal foil is a non-woven metal sheet containing aplurality of fabricated spaced apart openings or eyes, each eye sized totrap a predetermined range of particulate matter and lying insubstantially the same plane as all other eyes (prior to corrugation).

Density of cells of a corrugated pattern is the number of flow channelsper unit area of a catalyst face.

High surface area is the surface area of all the microscopic pores in awashcoat layer as measured by the Brunauer, Emmett, and Teller (“BET”)method.

The tolerance range for cell density may be ±5 cells per in² (0.8 cellsper cm²), the term, about, indicating this range.

The tolerance range for mass loading of a washcoat layer may be ±12%,the term, about, indicating this range.

DETAILED DESCRIPTION

Referring to the drawings, a diesel engine emissions catalyst or dieseloxidation trap catalyst (“DOTC”) 10 of this disclosure includes astructure (substrate) 11 comprising one or more coated, corrugatedlayers 13 of micro-expanded metal foil 17 and a frame 15 housing orencapsulating the substrate 11. The metal foil layer 13 may be about0.002 inches thick (0.0508 mm). The micro-expanded metal foil 17includes small openings or eyes 19, The coated surface 21 may be a highsurface area, stabilized, and promoted washcoat layer 23. The corrugatedpattern 25 may include a herringbone-style pattern that, when in use, isoriented in a longitudinal direction L of the diesel engine exhaust flow(transverse T to the eye 19), with flow impinging on the metal foilstrand walls 23 surrounding the eyes 19.

The density of cells of the corrugated pattern 25—defined as the numberof flow channels 27 per unit area of the catalyst face 29—may be in arange of about IOU cells/in² (15 cells/cm²) to about 400 cells/in² (62cells/cm²), there being subranges within this broader range, as well asranges and subranges on either side. See Table 1.

TABLE 1 Example Cell Densities of Embodiments (per square area). in² cm²50 7.75 60 9.00 70 11.00 80 12.50 90 14.00 100 15.50 150 23.25 200 31.00250 38.75 300 46.50 350 54.25 400 62.00 450 69.75 500 77.50 550 85.25600 93.00 650 100.75 700 108.50 750 116.25 800 124.00

In embodiments, the metal foil 17 comprises an alloy suitable in itscomposition for use as a catalyst substrate. In some embodiments, themetal foil 17 may be a stainless steel alloy including aluminum oriron-chromium-aluminum (FeCrAl) alloy. By way of a non-limiting example,the alloy may be FECRALLOY™ alloy containing iron, chromium, andaluminum. The alloy may include chromium in a range of about 18 wt % toabout 24 wt %, there being subranges within this range, such as but notlimited to 19 wt % to 23 wt %, or 20 wt % to 22 wt %, and ranges thatoverlap these ranges (e.g. 21 wt % to 24 wt %). The alloy may includealuminum in a range of about 3 wt % to about 7 wgt %, there beingsubranges within this broader range.

The metal foil 17 may contain eyes 19 in a range of 0.020 inches to0.080 inches (0.058 mm to 2.032 mm), there being subranges within thisbroader range. The eyes 19 may be formed using a slitting process, withthe slit portion being moved or cold-formed to create the eye 19. Theeyes 19 may be spaced apart from one another both across the length andwidth of the foil 17. For example, a piercing tool may be used to piercea slit or cell and pull the surrounding metal to form the eye 19, withthe tool offsetting to perform another pierce-pull operation. Anexpanded metal machine the same as, or similar to, a BENMETAL® SP 750expanded metal machine may be used.

The metal foil 17 may be coated with a mixture of aluminum oxide and atleast one rare earth oxide and a promoter, of a type known to thoseskilled in the art, to form a high surface area washcoat layer 23. Thewashcoated layer 23 may include a precious metal, a combination of atleast two different precious metals, a non-precious metal catalyticallyreactive element, or some combination of a precious and a non-preciousmetal catalytically reactive element, the metals being ones known in theart and selected for the intended reaction. In some embodiments, theprecious metal may be a platinum group metal—ruthenium, rhodium,palladium, osmium, iridium, and platinum—or a platinum group metal alloyor bi-metallic catalyst. The precious metal may also comprise or includegold or silver. In embodiments, the mass loading of the washcoat layermay be about 1½ g/in³ (91.54 g/l) or in a range of 80.5 g/l to 102.5g/l. A precious metal loading may be on top of or in addition to thiswashcoat loading.

The coated substrate 11 may be encapsulated into a structural frame 15in which two or more substrates 11 may be combined into one largerstructure to facilitate installation into, or retention of, the catalyst10 in an exhaust duct, pipe, or reactor. The catalyst 10 may be orientedso that, when in use, the direction of the herringbone-style pattern isin a longitudinal direction of the diesel engine exhaust flow.

Referring to FIG. 7 , the catalyst 10 may be used in connection with aselective catalyst reduction (“SCR”) system 30 that mixes aliquid-reductant agent with an engine exhaust stream. The SCR system 30may include three main components: an injector 31 for theliquid-reductant agent, a mixing process 33 to mix the injected agentwith an engine exhaust stream, and a reactor 35 where the reductionreaction will occur. The mixing process 33 may include a mixing duct thesame as, or similar to one supplied by Catalytic Combustion Corp.(Bloomer, Wis.) for use in an SCR system. The injector 31 may be incommunication with a control system (not shown). Typically, theliquid-reductant agent is an automotive grade urea known as dieselexhaust fluid (“DEF”). The ammonia needed for NOx reduction may coarsefrom the hydrolysis of the urea solution or from either anhydrous, oraqueous ammonia that is injected and evaporated within an exhaust duct,pipe, or reactor. The catalyst 10 of this invention may be placedupstream of the mixing process 33 of the SCR system 30 in a reactor 37.In some embodiments, the catalyst 10 may be housed within the reactor 35of the SCR system 30 with appropriate ductwork channeling the flow.

In some embodiments, the diesel engine used with the catalyst 10 may bea diesel engine configured for use in a nonroad application such asconstruction, agricultural, and industrial applications. In otherembodiments, the diesel engine may be an engine used in railwaylocomotives, marine vessels, or mining equipment. The catalyst 10 may beconfigured to achieve a known emissions standard such as EPA Tier 3,Tier 4, or other existing emission standards or a projected standardthat will be promulgated within the foreseeable future to achievenonroad emissions targets.

Using generally accepted engineering techniques, such as but not limitedto design of experiments, one or more features of the catalyst 10—suchas but not limited to the geometry of the eyes, the dimensionalspecifications of the herringbone-style pattern and the resulting celldensity as previously mentioned, the composition of the catalystwashcoat, and the level of platinum in the coating—may be adjusted tofurther characterize the operational parameters of the catalystformation and catalyst structure. By way of a non-limiting example, theeyes 19 may be diamond-shaped eyes or any shape and size required totrap the diesel particulate matter (“DPM”). In embodiments, the catalyst10 may achieve a 60% to 90% reduction of DPM, The amount of preciousmetals may be in a range of about 2 g/ft³ to about 40 g/ft³ (0.071 g/lto 1.41 g/l), there being subranges within these broader ranges. SeeTable 2.

TABLE 2 Example Amounts of Precious Metal in Embodiments. g/ft3 g/l 20.071 3 0.106 4 0.141 5 0.177 6 0.212 7 0.247 8 0.283 9 0.318 10 0.35311 0.388 12 0.424 13 0.459 14 0.494 15 0.530 16 0.565 17 0.600 18 0.63619 0.671 20 0.706 21 0.742 22 0.777 23 0.812 24 0.848 25 0.883 26 0.91827 0.953 28 0.989 29 1.024 30 1.059 31 1.095 32 1.130 33 1.165 34 1.20135 1.236 36 1.271 37 1.307 38 1.342 39 1.377 40 1.413

In embodiments, a method of making a diesel engine emissions catalyst ofthis disclosure includes micro-expanding the metal foil 17 to provideeyes 19 and then passing the micro-expanded foil 17 through acorrugation process to emboss a herringbone-style pattern 25 on the foil17. The corrugated foil 17 may be passed through heat or thermaltreatment, acid etching, or some combination of the two to enhancesurface area. Either before or after being formed into a structure(substrate) 11 suitable for installation into an exhaust duct, pipe, orreactor, the foil 17 may be coated with a mixture of aluminum oxide andat least one rare earth oxide and a promoter, of a type known to thoseskilled in the art, to form a high surface area washcoat layer 23. Themixture may contain various amounts of the gamma, delta, eta, or alphaalumina crystalline phases. The ratios between the crystalline phasescan be varied in order to achieve the desired parameters of thewashcoat. In this context, high surface area refers to the surface areaof all the microscopic pores in the alumina materials. In embodiments,the surface area, as measured by the Brunauer, Emmett, and Teller(“BET”) method may be in a range of about 100 m²/g to about 250 m²/g(488,246 ft²/lb to 1,220,616 ft²/lb), there being sub-ranges rangeswithin this broader range. See Table 3.

TABLE 3 Example High Surface Area of Washcoat Layer in Embodiments. m²/gft²/lb 100 488246 110 537071 120 585896 130 634720 140 683545 150 732370160 781194 170 830019 180 878844 190 927668 200 976493 210 1025318 2201074142 230 1122967 240 1171791 250 1220616

The washcoated layer 23 may be impregnated with a precious metal, acombination of at least two different precious metals, a non-preciousmetal catalytically reactive element, or some combination of a preciousand a non-precious metal catalytically reactive element, the metalsbeing ones known in the art and selected for the intended reaction,Impregnation may occur after the washcoat or may be incorporated intothe washcoat materials prior to deposition onto the corrugated foil 17.

A catalyst 10 of this disclosure may be used in an SCR system configuredto reduce diesel DPM, nitrogen oxides (“NO_(x),”) carbon monoxide(“CO”), and non-methane, non-ethane hydrocarbons (“NMNEHC”). The SCRsystem may be configured to achieve a predetermined emission standardsuch as, but not limited to, EPA Tier 3, Tier 4, and other existingemission standards and projected standards that will be promulgatedwithin the foreseeable future to achieve nonroad emissions targets.

Embodiments of a diesel engine emissions catalyst of this disclosure mayinclude one or more of the following features:

-   -   a substrate including one or more coated, corrugated,        micro-expanded metal foil layers;    -   each layer containing a plurality of eyes;    -   a cell density of the corrugated pattern being in a range of        about 100 cells/in² (15 cells/cm²) to about 400 cells/in² (62        cells/cm²) or in a range or subrange of Table 1;    -   eyes with openings in a range of about 0.020 inches to about        0.080 inches (0.058 mm to 2.032 mm);    -   openings that are circular shaped;    -   openings that are diamond-shaped;    -   a coating of each said layer including a precious metal, a metal        oxide, and a porous surface area;    -   a porous surface area in a range of about 100 m²/g to about 250        m²/g (488,246 ft²/lb to 1,220,616 ft²/lb) or in a range or        subrange of Table 3;    -   a mass loading of the washcoat layer of about 1½ g/in³ (91.54        g/l);    -   a mass loading of the washcoat layer in a range of 80.5 g/l to        102.5 g/l.    -   a frame housing the substrate;    -   a metal of each said metal foil layers including chromium;    -   a metal of each said metal foil layers including aluminum;    -   a metal foil layer being a heat treated metal foil layer;    -   a metal foil layer being an acid etched layer;    -   a metal foil layer being a thermally treated metal foil layer;    -   an amount of the precious metal being in a range of about 2        g/ft³ to about 40 g/ft³ (0.071 g/l to 1.41 g/l) or in a range or        subrange of Table 2;    -   the precious metal being at least one platinum group metal;    -   the precious metal including two or more precious metals;    -   the precious metal being part of a mixed metal including at        least one non-precious metal;    -   the metal oxide being aluminum oxide;    -   a coating including a metal oxide;    -   the coating including a rare earth oxide;    -   the coating including a precious metal oxide;    -   the coating including a promotor;    -   each metal foil layer including a herringbone pattern;    -   a herringbone pattern configured for orientation in a        longitudinal direction of a diesel engine exhaust flow.

Experimental Field Test Results

A heavy duty diesel engine designed for locomotive applications wasoutfitted with an SCR system which contained an amount of a DOTC of thisdisclosure appropriate to the exhaust flow rate and raw DPM emissions.The engine was installed into a locomotive and was employed by a trainoperation in a normal manner for a period of 3000 hours. DPM emissionswere measured at the initial commissioning, after 1500 hours ofoperation, and after 3000 hours of operation to assess whether thecatalyst worked for its intended purpose, including determining theremoval efficiency of the DOTC and to determine if the removalefficiency was undergoing in-service degradation. The DPM levels weremeasured using a gravimetric technique approved for this purpose by boththe US Environmental Protection Agency (“EPA”) and the California AirResources Board (“CARE”). Additionally, at the time of measurement, theengine was operated in two representative operational cases, with Case 1being typical for locomotive moving a train over a distance and Case 2being typical for a locomotive moving cars around a train yard in theact of assembling a train for eventual distance travel. Case 2 isregarded, on the basis of having a higher level of uncontrolled DPM fromthe engine, as being the more severe test of the catalyst.

As shown in FIG. 10 and in Table 4 below, the removal efficiencies inboth case and case 2 remained relatively constant, showing nodegradation over time. The average DOTC removal efficiencies of about63% and 70% for Cases 1 and 2, respectively, are higher than thattypically achieved by prior art oxidation catalysts. See Table 5.Although the removal efficiency is not above that of diesel particulatefilters, which can achieve about a 95% conversion or more, the DOTC didnot induce the higher backpressure on the engine that these filtersinduce.

TABLE 4 DOTC Removal Efficiency - Locomotive Field Trial. PercentRemoval Hours Case 1 Case 2 0 62.9 69.0 1500 59.1 63.4 3000 68.3 77.0Overall Avg. 63.4 69.8

TABLE 5 Removal Efficiency Comparison of DOTC Field Trial Results toPrior Art. Ratio of DOTC Efficiency Typical to Prior Art Prior ArtEfficiency Efficiency Case 1 - Case 2 - Prior Art % 63% 70% Catalyst 203.15 3.50 40 1.58 1.75 Filter 95 0.66 0.74

While embodiments of a diesel engine emissions catalyst and method ofmanufacture and use have been described, the catalyst is capable ofmodification by persons of ordinary skill in the art without departingfrom the scope of this disclosure. The claims include the full range ofequivalents to which each element is entitled.

The invention claimed is:
 1. A diesel engine emissions catalyst (10)comprising: a substrate (11) including a plurality of coated,corrugated, micro-expanded metal foil layers (13), each of said layersoverlapping an adjacent layer of the plurality to form open flowchannels in between; and a coating of each said layer comprising awashcoat layer (23) and a precious metal oxide.
 2. A diesel engineemissions catalyst (10) according to claim 1, a metal of each said metalfoil layers (13) including chromium and aluminum.
 3. A diesel engineemissions catalyst (10) according to claim 1, each said metal foil layer(13) being a heat treated metal foil layer.
 4. A diesel engine emissionscatalyst (10) according to claim 1, each said metal foil layer (13)being an acid etched or thermally treated metal foil layer.
 5. A dieselengine emissions catalyst (10) according to claim 1, the precious metalbeing platinum.
 6. A diesel engine emissions catalyst (10) to claim 1,the metal oxide being aluminum oxide.
 7. A diesel engine emissionscatalyst (10) according claim 1, further comprising the washcoat layer(23) including a rare earth oxide.
 8. A diesel engine emissions catalyst(10) according claim 1, further comprising the washcoat layer (23)including a promotor.
 9. A diesel engine emissions catalyst (10)according to claim 1, each said metal foil layer (13) including aherringbone pattern configured for orientation in a longitudinaldirection (L) of a diesel engine exhaust flow.
 10. A diesel engineemissions catalyst (10) according to claim 1, wherein: each said layercontaining a plurality of eyes (19) with diamond-shaped openings in arange of 0.058 mm to 2.032 mm and arranged in a herringbone pattern. 11.A diesel engine emissions catalyst (10) according to claim 1, wherein:the washcoat layer (23) being in a range of 80.5 g/l to 102.5 g/l,including a metal oxide; the precious metal being in a range of 0.071g/l to 1.41 g/l.
 12. A diesel engine emissions catalyst (10) accordingto claim 11, wherein: said washcoat layer has a porous surface area in arange of 100 m²/g to 250 m²/g of the metal oxide.
 13. A diesel engineemissions catalyst (10) according to claim 1, wherein: the open flowchannels (27) per unit area of a face of the substrate (11) being in arange of 15 cells/cm² to 62 cells/cm².
 14. A method for reducing dieselparticulate emissions, the method comprising: passing a diesel engineexhaust gas flow through a diesel engine emissions catalyst (10)comprising: a substrate (11) including a plurality of coated,corrugated, micro-expanded metal foil layers (13), each of said layersoverlapping an adjacent layer of the plurality to form open flowchannels in between; and a coating of each said layer comprising awashcoat layer (23) and a precious metal oxide.
 15. A method accordingto claim 14, a metal of at least one metal foil layers (13) includingstainless steel.
 16. A method according to claim 14, at least one metalfoil layer (13) being at least one of a heat treated metal foil layer,an acid etched metal foil layer, and a thermally treated metal foillayer.
 17. A method according to claim 14, the precious metal beingplatinum.
 18. A method according to claim 14, the metal oxide beingaluminum oxide.
 19. A method according claim 14, further comprising thewashcoat layer (23) including a rare earth oxide, a promotor, or boththe rare earth oxide and the promotor.
 20. A method according to claim14, wherein: each of said layers overlapping an adjacent layer of theplurality to form open flow channels in between, each said layercontaining a plurality of eyes (19) with diamond-shaped openings in arange of 0.058 mm to 2.032 mm and arranged in a herringbone pattern. 21.A method according to claim 14, wherein: the washcoat layer (23) beingin a range of 80.5 g/l to 102.5 g/l, including a metal oxide, theprecious metal being in a range of 0.071 g/l to 1.41 g/l.
 22. A methodaccording to claim 21, wherein: said washcoat layer has a porous surfacearea in a range of 100 m²/g to 250 m²/g of the metal oxide.
 23. A methodaccording to claim 14, wherein: the open flow channels (27) per unitarea of a face of the substrate (11) being in a range of 15 cells/cm² to62 cells/cm².
 24. A diesel engine emissions catalyst (10) comprising: asubstrate (11) including a plurality of coated, corrugated, metal foillayers (13), each of said layers overlapping an adjacent layer of theplurality to form open flow channels in between; a coating of each saidlayer comprising a washcoat layer (23) and a precious metal oxide, andhaving a porous surface area in a range of 100 m²/g to 250 m²/g of themetal oxide.
 25. A diesel engine emissions catalyst (10) according toclaim 24, wherein: each said layer containing a plurality of eyes (19)with diamond-shaped openings in a range of 0.058 mm to 2.032 mm andarranged in a herringbone pattern.
 26. A diesel engine emissionscatalyst (10) according to claim 24, wherein: the washcoat layer (23)being in a range of 80.5 g/l to 102.5 g/l, including a metal oxide. 27.A diesel engine emissions catalyst (10) according to claim 24, wherein:the precious metal being in a range of 0.071 g/l to 1.41 g/l.
 28. Adiesel engine emissions catalyst (10) according to claim 24, wherein:the open flow channels (27) per unit area of a face of the substrate(11) being in a range of 15 cells/cm² to 62 cells/cm².
 29. A dieselengine emissions catalyst (10) according to claim 24, wherein: saidmetal foil layers are micro-expanded.
 30. A method for reducing dieselparticulate emissions, the method comprising: passing a diesel engineexhaust gas flow through a diesel engine emissions catalyst (10)comprising: a substrate (11) including a plurality of coated,corrugated, metal foil layers (13), each of said layers overlapping anadjacent layer of the plurality to form open flow channels in between; acoating of each said layer comprising a washcoat layer (23) and aprecious metal oxide, and having a porous surface area in a range of 100m²/g to 250 m²/g of the metal oxide.
 31. A method for reducing dieselparticulate emissions according to claim 30, wherein: each said layercontaining a plurality of eyes (19) with diamond-shaped openings in arange of 0.058 mm to 2.032 mm and arranged in a herringbone pattern. 32.A method for reducing diesel particulate emissions according to claim30, wherein: the washcoat layer (23) being in a range of 80.5 g/l to102.5 g/l, including a metal oxide.
 33. A method for reducing dieselparticulate emissions according to claim 30, wherein: the precious metalbeing in a range of 0.071 g/l to 1.41 g/l.
 34. A method for reducingdiesel particulate emissions according to claim 30, wherein: the openflow channels (27) per unit area of a face of the substrate (11) beingin a range of 15 cells/cm² to 62 cells/cm².
 35. A method for reducingdiesel particulate emissions according to claim 30, wherein: said metalfoil layers are micro-expandable.
 36. A diesel engine emissions catalyst(10) comprising: a substrate (11) including a plurality of coated,corrugated, micro-expanded metal foil layers (13), each of said layersoverlapping an adjacent layer of the plurality to form open flowchannels in between.